1. Field of the Invention
The present invention relates to enhanced wireless telecommunications service using location-based services, and more particularly to systems and methods for controlling location-determination in a wireless communication system.
2. Description of Related Art
Wireless service providers have been developing techniques for determining the geographical location of a wireless communication device (WCD), such as a cell phone or wirelessly-equipped PDA or computer. Wireless service providers are primarily motivated to implement such techniques by the need to interface with emergency services such as enhanced 911. Nevertheless, as location determination techniques have become more precise and more accurate, wireless service providers are finding many more applications that use location determination techniques. For example, an application now available allows a user of one WCD to determine the geographical location of the user of another WCD. Other applications provide users with useful information based on their geographical position, such as the location of the nearest service station or the nearest restaurant.
Efforts by wireless service providers to improve location-based services have been complicated by the need to work with a variety of third party providers, such as location-based service providers, and vendors of location-determination equipment.
By way of example, wireless service providers typically work with third party Public Safety Access Points (PSAP), which provide 911 emergency services. Further, wireless service providers typically work with third party vendors of location-determination systems, including components such as a “mobile positioning center” (MPC) for instance. When a WCD places a 911 call, the wireless service provider may connect the call to the PSAP and may further employ the location-determination system to determine the location of the WCD and to report the location to the PSAP.
In typical practice, to determine the location of the WCD, the MPC will invoke position determining equipment (PDE), which can determine the location of the WCD in various ways. One way the PDE could determine the WCD location is through triangulation. Triangulation would typically provide a latitude/longitude reading together with an uncertainty value. Another way that is usually more accurate is by sending a location-determination request message to the WCD itself and having the WCD employ a GPS (global positioning system) module or other mechanism to determine its own location. The WCD would then return an indication of its location, also typically as a latitude/longitude reading together with an uncertainty value, back to the MPC.
While standards have been implemented to govern communications between a wireless carrier and location-based services (such as PSAPs), including communications between an MPC and the location-based service for instance, specific implementations can exhibit unexpected behavior that may affect operations in the wireless network or that may be contrary to the desires of the wireless service provider or others.
For example, one problem that can occur is that a location-based service may repeatedly request the MPC to report the location of the calling WCD. In the arrangement where the MPC determines the WCD location by querying the WCD itself, each time the MPC does so the WCD may switch from using its primary voice transceiver (which it may be using to communicate with the location-based service) to using a GPS receiver or other logic so as to determine its location and report its location back to the MPC. Consequently, if the location-based service repeatedly requests the MPC to report the location of the WCD, multiple disruptions of the voice call could occur. Even though these disruptions may be brief, they are undesirable.
As another example, an MPC may be arranged to provide a response to a position request in a standard format, providing a standard set of information. Yet some location-based service providers, such as some PSAPs, might want to have the position response data be formatted in a special manner or to include or exclude certain information. Unfortunately, if the MPC is set to provide position responses in a standard, fixed format, it may not be possible to accommodate the format desires of these location-based services.
Further, an MPC is typically configured to apply a fixed set of location-determination logic when determining the location of any WCD, and the wireless service provider will have little if any control over the manner in which that location-determination logic operates. If the wireless service provider wants to modify the operation of the MPC in some way, the wireless service provider would typically need to work with the MPC vendor to arrange for revisions of the MPC program logic, which can be both time consuming and expensive.